by Cristian Ciocaltea

[permalink] [raw]

Subject: Re: [PATCH v2 3/6] soc: actions: Add Actions Semi Owl socinfo driver

On Fri, Apr 02, 2021 at 11:46:24PM +0530, Manivannan Sadhasivam wrote:
> On Tue, Mar 30, 2021 at 04:48:18PM +0300, Cristian Ciocaltea wrote:
> > The driver provides information about the Action Semi Owl family of
> > SoCs (S500, S700 and S900) to user space via sysfs: machine, family,
> > soc_id, serial_number.
> >
> > Note the serial number is currently provided only for the S500 SoC
> > variant.
> >
> > Signed-off-by: Cristian Ciocaltea <[email protected]>
> > ---
> > drivers/soc/actions/Kconfig | 8 +
> > drivers/soc/actions/Makefile | 1 +
> > drivers/soc/actions/owl-socinfo.c | 152 ++++++++++++++++++
> > include/linux/soc/actions/owl-serial-number.h | 20 +++
> > 4 files changed, 181 insertions(+)
> > create mode 100644 drivers/soc/actions/owl-socinfo.c
> > create mode 100644 include/linux/soc/actions/owl-serial-number.h
> >
> > diff --git a/drivers/soc/actions/Kconfig b/drivers/soc/actions/Kconfig
> > index 1aca2058a40c..15faade9282d 100644
> > --- a/drivers/soc/actions/Kconfig
> > +++ b/drivers/soc/actions/Kconfig
> > @@ -14,4 +14,12 @@ config OWL_PM_DOMAINS
> > power-gating on Actions Semiconductor S500, S700 and S900 SoCs.
> > If unsure, say 'n'.
> >
> > +config OWL_SOCINFO
> > + bool "Actions Semi Owl SoC info driver"
> > + default ARCH_ACTIONS
> > + select SOC_BUS
> > + help
> > + Say 'y' here to support the Action Semiconductor Owl socinfo
>
> Actions Semi
>
> > + driver, providing information about the SoC to user space.
> > +
> > endif
> > diff --git a/drivers/soc/actions/Makefile b/drivers/soc/actions/Makefile
> > index 4db9e7b050e5..4b2591d3089f 100644
> > --- a/drivers/soc/actions/Makefile
> > +++ b/drivers/soc/actions/Makefile
> > @@ -2,3 +2,4 @@
> >
> > obj-$(CONFIG_OWL_PM_DOMAINS_HELPER) += owl-sps-helper.o
> > obj-$(CONFIG_OWL_PM_DOMAINS) += owl-sps.o
> > +obj-$(CONFIG_OWL_SOCINFO) += owl-socinfo.o
> > diff --git a/drivers/soc/actions/owl-socinfo.c b/drivers/soc/actions/owl-socinfo.c
> > new file mode 100644
> > index 000000000000..f28eafac3792
> > --- /dev/null
> > +++ b/drivers/soc/actions/owl-socinfo.c
> > @@ -0,0 +1,152 @@
>
> [...]
>
> > + * Access SoC's serial number stored by the bootloader in DDR memory.
> > + */
> > +static int owl_socinfo_read_serial_rmem(struct device *dev)
> > +{
> > + struct reserved_mem *rmem;
> > + struct device_node *np;
> > + int ret = 0;
> > +
> > + np = of_find_compatible_node(NULL, NULL, "actions,owl-soc-serial");
> > + if (!np)
> > + return -ENXIO;
> > +
> > + rmem = of_reserved_mem_lookup(np);
>
> If you do this correctly, you could use "pdev->dev.of_node" here instead of
> using "of_find_compatible_node()" for getting np.

Right, as previously explained, my intention was to avoid binding the
driver on the serial number node in order to keep it generic enough.

> > + if (!rmem) {
> > + dev_err(dev, "failed to acquire reserved memory region\n");
> > + ret = -EINVAL;
> > + goto out_put;
> > + }
> > +
>
> [...]
>
> > +static const struct of_device_id owl_socinfo_of_match[] = {
> > + { .compatible = "actions,s500-soc", .data = &s500_soc_info, },
> > + { .compatible = "actions,s700-soc", .data = &s700_soc_info, },
> > + { .compatible = "actions,s900-soc", .data = &s900_soc_info, },
>
> Please don't add S700/S900 for now.

I assumed we can use the driver for S700/S900, even though the serial
number is not provided for them.

> > + { }
> > +};
> > +
> > +static struct platform_driver owl_socinfo_platform_driver = {
> > + .probe = owl_socinfo_probe,
> > + .driver = {
> > + .name = "owl-socinfo",
> > + .of_match_table = owl_socinfo_of_match,
> > + },
> > +};
> > +
> > +static int __init owl_socinfo_init(void)
> > +{
> > + return platform_driver_register(&owl_socinfo_platform_driver);
> > +}
> > +subsys_initcall(owl_socinfo_init);
> > diff --git a/include/linux/soc/actions/owl-serial-number.h b/include/linux/soc/actions/owl-serial-number.h
> > new file mode 100644
> > index 000000000000..f8595417668f
> > --- /dev/null
> > +++ b/include/linux/soc/actions/owl-serial-number.h
> > @@ -0,0 +1,20 @@
> > +/* SPDX-License-Identifier: GPL-2.0+ */
> > +/*
> > + * Copyright (c) 2021 Cristian Ciocaltea <[email protected]>
> > + */
> > +
> > +#ifndef __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__
> > +#define __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__
> > +
> > +#if IS_ENABLED(CONFIG_OWL_SOCINFO)
> > +u32 owl_get_soc_serial_low(void);
> > +u32 owl_get_soc_serial_high(void);
>
> Where are these APIs used?

This will be used by the Ethernet MAC driver to generate a stable
address. Initially I used the global 'system_serial_{low,high}'
variables to pass this information outside the driver, but that is
not portable, i.e. only supported on ARM32, not ARM64.

Thanks for the review,
Cristi

> Thanks,
> Mani
>
> > +#else
> > +static inline u32 owl_get_soc_serial_low(void)
> > +{ return 0; }
> > +
> > +static inline u32 owl_get_soc_serial_high(void)
> > +{ return 0; }
> > +#endif /* CONFIG_OWL_SOCINFO */
> > +
> > +#endif /* __SOC_ACTIONS_OWL_SERIAL_NUMBER_H__ */
> > --
> > 2.31.1
> >

2021-04-02 19:45:36

by Cristian Ciocaltea

[permalink] [raw]

Subject: Re: [PATCH v2 1/6] dt-bindings: reserved-memory: Add Owl SoC serial number binding

On Fri, Apr 02, 2021 at 11:36:07PM +0530, Manivannan Sadhasivam wrote:
> On Thu, Apr 01, 2021 at 08:40:01PM +0300, Cristian Ciocaltea wrote:
> > On Thu, Apr 01, 2021 at 12:07:04PM -0500, Rob Herring wrote:
> > > On Tue, Mar 30, 2021 at 04:48:16PM +0300, Cristian Ciocaltea wrote:
> > > > Add devicetree binding for the Actions Semi Owl SoC serial number
> > > > reserved-memory range.
> > > >
> > > > Signed-off-by: Cristian Ciocaltea <[email protected]>
> > > > ---
> > > > .../actions,owl-soc-serial.yaml | 53 +++++++++++++++++++
> > > > 1 file changed, 53 insertions(+)
> > > > create mode 100644 Documentation/devicetree/bindings/reserved-memory/actions,owl-soc-serial.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/reserved-memory/actions,owl-soc-serial.yaml b/Documentation/devicetree/bindings/reserved-memory/actions,owl-soc-serial.yaml
> > > > new file mode 100644
> > > > index 000000000000..41b71f47ee6c
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/reserved-memory/actions,owl-soc-serial.yaml
> > > > @@ -0,0 +1,53 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/reserved-memory/actions,owl-soc-serial.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Actions Semi Owl reserved-memory for SoC serial number
> > > > +
> > > > +maintainers:
> > > > + - Cristian Ciocaltea <[email protected]>
> > > > +
> > > > +description: |
> > > > + Provide access to the memory region where the two parts of the Actions
> > > > + Semi Owl SoC serial number (low & high) can be read from. This information
> > > > + is provided by the bootloader, hence expose it under /reserved-memory node.
> > > > +
> > > > + Please refer to reserved-memory.txt in this directory for common binding
> > > > + part and usage.
> > > > +
> > > > + This is currently supported only on the S500 SoC variant.
> > > > +
> > > > +properties:
> > > > + compatible:
> > > > + oneOf:
> > > > + - const: actions,owl-soc-serial
> > > > + - items:
> > > > + - enum:
> > > > + - actions,s500-soc-serial
> > > > + - const: actions,owl-soc-serial
> > > > +
> > > > + reg:
> > > > + maxItems: 1
> > > > +
> > > > +required:
> > > > + - compatible
> > > > + - reg
> > > > +
> > > > +additionalProperties: true
> > > > +
> > > > +examples:
> > > > + - |
> > > > + reserved-memory {
> > > > + #address-cells = <1>;
> > > > + #size-cells = <1>;
> > > > + ranges;
> > > > +
> > > > + soc_serial: soc-serial@800 {
> > > > + compatible = "actions,s500-soc-serial", "actions,owl-soc-serial";
> > > > + reg = <0x800 0x8>;
> > >
> > > You end up wasting a whole page of memory for 8 bytes. It may be better
> > > to copy this to a DT property ('serial-number' is already a defined root
> > > property).
> >
> > Actually there is more information provided by the vendor bootloader
>
> Then you should call it as socinfo or something not soc_serial.

Agree, maybe 'bootinfo' or 'fwinfo', to suggest it is coming from
firmware / bootloader.

Thanks for reviewing,
Cristi

> Thanks,
> Mani
>
> > in this memory page, so we might use it once we are able to decode it.
> > For the moment I could only identify the serial number.
> >
> > Thanks,
> > Cristi
> >
> > > Rob